Climate change: information kit

Human activities are releasing greenhouse gases into the atmosphere. Carbon dioxide is produced when fossil fuels are used to generate energy and when forests are cut down and burned. Methane and nitrous oxide are emitted from agricultural activities, changes in land use, and other sources. Artificial chemicals called halocarbons [CCFCs, HFCs, PFCs] and other long-lived gases such as sulphur hexafluoride (SF6) are released by industrial processes. Ozone in the lower atmosphere is generated indirectly by automobile exhaust fumes and other sources.